examples: use QVector<QPointF> instead of QList<QPointF>

examples: use QVector<QPointF> instead of QList<QPointF>

QPointF is in the category of types for which QList
is needlessly inefficient (elements are copy-constructed
onto the heap and held through pointers). Use a vector
instead. This is consistent with the QPainter API.

Change-Id: Id0e910c067a60d12fbc175e7ee7da824834be374
Reviewed-by: hjk <qthjk@ovi.com>
Reviewed-by: Lars Knoll <lars.knoll@nokia.com>